In recent years, energy saving has been actively promoted as a measure against global warming that is a global environmental problem. For example, in various kinds of cooling/warming equipment such as refrigerators and vending machines, a configuration has been employed in which a heat-insulating space between an outer box and an inner box of a heat-insulating box that forms the main body of the equipment is filled with a “closed-cell urethane foam” and the urethane foam is foamed. However, from the viewpoint of energy saving, a transition is being made from the above-mentioned configuration to a configuration in which the heat-insulating space is filled with a “closed-cell urethane foam” and the urethane foam is foamed after a “vacuum heat-insulating material” is disposed in the heat-insulating space. This vacuum heat-insulating material is formed in the following manner: a core material formed of glass wool or the like is decompression-sealed in a bag-shaped outer casing material having gas barrier properties. Further, some vacuum heat-insulating materials are formed by decompression-sealing an adsorption material together with a core material. Vacuum heat-insulating materials have heat-insulating performance that is about 20 times as great as the heat-insulating performance of hard urethane foams. Thus, vacuum heat-insulating materials have such excellent characteristics that even when the thickness is reduced, sufficient heat-insulating performance is achieved. Therefore, vacuum heat-insulating materials satisfy customer needs to increase the volume of the inside of a heat-insulating box by thinning the heat-insulating box. Moreover, vacuum heat-insulating materials attract attention as an effective tool for saving energy by improving heat-insulating performance.
However, heat-insulating spaces of heat-insulating boxes of refrigerators and the like generally have a complicated shape. Thus, a covering area of the vacuum heat-insulating material, i.e. a ratio of the area of the vacuum heat-insulating material to the total heat transfer area of the heat-insulating box is limited. Thus, Patent Literature 1 proposes a technique in which a heat-insulating space of a heat-insulating box is filled with an “open-cell urethane foam” from an air feeding port for blow molding in the heat-insulating box and the urethane foam is foamed, followed by evacuating the inside of the heat-insulating box to vacuum using a vacuum exhaust apparatus connected to the air feeding port. The “open-cell” refers to a structure in which respective cells communicate with one another. The “closed-cell” refers to a structure in which respective cells are independent and do not communicate with one another.